Portable scaffold



Oct. 19, 1965 Filed Aug. 26, 1964 2 Sheets-Sheet 1 FI.G l I E v -i m MIROBERT L. DICKERSON INVENTOR.

ATTORNEYS Oct. 19, 1965 R. L. DICKERSON PORTABLE S CAFFOLD 2Sheets-Sheet 2 Filed Aug. 26, 1964 FIG FIG

ROBERT L. DIOKERSON INVENTOR.

ATTORNEYS United States Patent 3,212,605 PORTABLE SCAFFOLD Robert L.Dickerson, 3536 Stoneway, Seattle, Wash. Filed Aug. 26, 1964, Ser. No.392,095 7 Claims. (CL 182119) This invention relates to movablescaffolds and more particularly to a type of collapsible scaffold havingvertically adjustable work platforms. This is a continuationin-part ofpending application Serial Number 257,613, filed February 11, 1963,which is in turn a continuationin-part of abandoned application SerialNumber 128,463, filed August 1, 1961.

It is a principal object of my invention to provide a new and improvedscaffold which embodies novel details of construction in its frame workand in the means for removably securing the working platform to theframe when in use and when collapsed for storage.

Further objects of my invention are to provide a scaffold of this typewhich is sturdy, which is convenient both to use and to store, which caneasily be assembled in its expanded working position or collapsed to itsstorage position, and which is stable in both such positions.

These and other objects will appear in the course of the followingdescription and claims, the invention consisting in the novelconstruction and in the adaptation and combination of parts hereinafterdescribed and claimed.

In the accompanying drawings:

FIG. 1 is a side elevational view of a scaffold embodying the preferredteachings of my invention.

FIG. 2 is a detail horizontal sectional view taken on line 22 of FIG. 1.

FIG. 3 is a side elevational view showing the scaffold in collapsedposition.

, FIG. 4 is an end view of the scaffold while in collapsed condition.

FIG. 5 is a fragmentary vertical sectional view to an enlarged scaletaken on line 55 of FIG. 3; and

FIG. 6 is a detail vertical sectional view taken as indicated by line6-6 in FIG. 4 and with one of the platforms in working position on theupper rungs of the ladder sections.

Referring to the accompanying drawings it is seen that V the scaffold ofthe present invention comprises end ladder sections 12 which are joinedbetween the lower portions thereof by side parallel linkages 13. Theladder sections provide means to support working platforms 14 which maybe positioned at selected levels.

Each ladder section 12 includes a pair of corner posts 16 which are ofchannel form comprising a web 17 and spaced flanges 18-18. Verticallyspaced rungs 20 extend horizontally between each pair of corner postsand are welded to the flange 18'. The rungs also are of channel form andeach includes an upstanding outer flange 21 and an upstanding innerflange 23 'of reduced height connected by a horizontal web 22 providinga support for the ends of the platforms 14.

The platforms 14 may be solid wood planks or grates and to retain themon the rungs 20 I provide locating bars 24 which are riveted to thebottom side of the platforms at both ends thereof. When one of theplatforms is placed between a pair of horizontally aligned rungs, itsbars 24 fit into the channel grooves defined by the flanges 21 and 23 ofthe rungs. In this manner the platforms aid 3,212,605 Patented Oct. 19,1965 ice the side linkages 13 in holding the end ladder sections 12upright. The width of each working platform 14 is approximately one-halfthe length of the rungs 20 so that a pair of platforms may be placedside by side or at different levels. In the latter instance, theplatforms may be placed directly above one another or, as will morecommonly be the case, they maybe offset with respect to one another soas to be in a stepped arrangement.

Each corner post 16 rests on a related caster unit 25 anchored theretoby bolts 26. The caster wheels are swivel-mounted to permit the scaffoldto be moved along the ground surface in any direction and each isprovided with an individual braking device which provides for convenientlocking and release of the casters by means of related pedals 27-28. Thebraking device may be of the type described in United States Patent No.1,471,307.

The parallel linkages 13 at the longitudinal sides of the scaffold eachhave three-part upper and lower toggle mechanisms, the upper togglecomprising a right arm 30, elbow link 31, and left arm 32, while thecorresponding parts of the lower toggle are designated 33, 34 and 35.Each of the upper toggle arms is formed as a downturned channel of awidth to fit at its outer end between the flanges 18-18 of the relatedcorner post 16 and be pivotally connected therewith by bolts 36. Theupper elbow links 31 may be formed of the same channel stock as theposts 16 so as to fit over the inner ends of the upper toggle arms andbe pivotally connected thereto by bolts 37 in similar manner to theconnection 36 between the outer ends of arms and the corner posts.

It will be noted that the inner ends of each set of the upper togglearms are spaced apart to receive the upper end portion of a verticalconnecting rod 38 the-rebetween. These rods 38 are secured to theflanges 31a of the upper elbow links 31 by a cross-bar 40 which passesby necked threaded ends 40a through the flanges 31a, the rods 38 andrelated washers 41, and receives nuts 42. In addition to functioning asa pair of bolts, the cross-bar 40 also serves as both a centercross-brace and as a lift handle by which the toggle mechanisms can beupwardly broken to collapse the scaffold.

Instead of being of channel stock, the lower elbow links 34 and lowertoggle arms 33, 35 are formed from flat bar stock. At their outer endsthe lower toggle arms rests against the outer back face of the innerposts 16, and at their inner ends they occupy a position behind therelated elbow links 34. Bolts 43 and 44 pivotally connect the lowertoggle arms to the corner posts and the links 34, respectively.

At their lower end the inner faces of the rods 38 are cut back as shownin FIG. 5 to present flat surfaces 38a opposing the outer faces of thelinks 34 and shoulders 38b bearing against the upper edge of the links.Bolts 45 connect the rods 38 and links together. In this regard,although not detectable in the drawings, the vertical distance at eachside of the scaffold between the pivots 37 and 44 on the links 31 and 34is made slightly greater than the vertical spacing on each post 16between the pivots 36 and 43 so that when the scaffold is in itsexpanded position (FIG. 1), the pivots 44 are past center, i.e. thepivots 44 are slightly below the level of the pivots 43 whereas theupper pivots 36 and 37 are in coplanar horizontal alinement. Thisarrangement serves as a lock to resist any tendency for the scaffold tofold up while being moved about in its expanded operational condition.

The side parallel linkages 13 each include a pair of diagonal kneebraces 46-46 which are pivotally connected at their lower ends to thecorner posts 16 by the bolts 43. From the lower end of the related posts16 the knee braces of each pair converges upwardly to bolts 37 servingas pivots between the braces and a respective slide block 48. Theseblocks 48 are sleeved on the rods 38 and bear against the lower edge ofthe flanges 31a of the upper elbow links 31 when the scaffold isexpanded. During collapsing of the scaffold the blocks 48 ride down therods 38 toward the lower el bow links 34 as shown in FIG. 3.

Each ladder section 12 is provided with a vertically adjustable handrail unit 50 which is of channel crosssection and invertedU-configuration providing vertical legs 51 depending from the ends ofthe rail proper, denoted 52. The rail legs 51 are slidably received bythe corner posts 16 and each has its channel flanges 51a directed towardthe outer flange 18 of the respective corner post to receive a nut 53therebetween. Each of these nuts 53 is threaded onto a locking screw 54which passes outwardly through the outer flange 18 of the related postto a handle head 54a. When the locking screws 54 are tightened they bearagainst the web 51b of the rail legs and force them against the innerflanges 18 of the corner posts thereby locking the hand rail units 50against vertical movement. Raising or lowering of the hand rails 50 tothe desired height is readily accomplished by manually turning theexposed handles 54a to release the screw locks on the rail legs 51,slide adjusting the elevation of the hand rails, and then resetting thelocking screw 54.

As can be seen in FIG. 3, a pair of hanger cleats 55 is screw-connectedto the underside of each of the platforms 14 and is arranged to hookover the outer flange 21 of one of the rungs 20 when the platform isplaced on end. In this manner the platforms 14 may be convenientlystored with the rest of the scaffold.

To erect the scaffold into its work position, the platforms 14 arelifted to free their hanger cleats 55, the ladder sections are pulledapart to fully expand the side linkages 13 and lower the pivots 44 pastcenter. Then the platforms 14 are placed at the desired height orheights on the respective rungs 20 with the locating bars 24 of eachplatform seated on the web 22 and fitting between the flanges 21 and 23of the rungs. With the locating bars so engaged the platforms areretained in fixed position and contribute to the stability of theplatform. The hand rails 52 may be moved to the desired height andlocked in position as afore described. In use, the workman can easilyroll the scaffold on its casters 26 from place to place on the work siteand set the caster brakes for safety.

T o prepare the scaffold for compact storage, the hand rails 52 arelowered by releasing the locking screws 54, the platforms 14 are liftedfrom the ladder sections 12, the cross bar 40 is lifted to collapse thescaffold, and the platforms are hung by their cleats 55 on one of therungs 20.

It is thought that the invention will have been clearly understood fromthe foregoing detailed description. Changes in the details ofconstruction will suggest themselves and may be resorted to withoutdeparting from the spirit of the invention, wherefore it is my intentionthat no limitations be implied and that the hereto annexed claims begiven a scope fully commensurate with the broadest interpretation towhich the employed language admits.

What I claim as new is:

1. A collapsible scaffold comprising, an exposed pair of vertical endsupport sections each including a pair of laterally spaced posts,parallel side linkages connected between the posts of said end sectionsfor vertical jackknifing action whereby the end sections may be expandedto a fully spaced working position or brought close together to acollapsed storage :position, each of said parallel side linkages havingupper and lower parallel toggle mechanisms, each said upper togglemechanism including a center upper elbow section and a pair of uppertoggle arms pivotally connected to the upper elbow section and to theend posts at the respective side of the scaffold, and each said lowertoggle mechanism including a center lower elbow section and a pair oflower toggle arms pivotally connected to the lower elbow section and tothe end posts at the respective side of the scaffold, a respectivevertical connecting bar in each of said parallel side linkages extendingbetween the upper and lower elbow sections thereof, a respective slideblock sleeved on each of said connecting bars, and a respective pair ofdiagonal knee braces in each of said parallel side linkages pivotallyconnected to the respective said slide block and to the end posts at therespective side of the scaffold.

2. The scaffold of claim 1 in which said vertical connecting bars areinterconnected by a transverse bracing bar whereby collapsing of saidscaffold may be accomplished by pulling said bracing bar upwardly.

3. The scaffold of claim 1 in which the lower elbow links are sprungdownwardly past center when the scaffold is in its expanded workingposition.

4. The scaffold of claim 1 in which each of said end posts has arespective caster unit at its lower end comprising a caster wheel and alock mechanism for selectively locking the wheel.

5. The scaffold of claim 1 in which one of said end sections carries atransverse hand rail with legs at its end depending into the posts ofthe respective end section, each of said legs having a channelcross-section, and a respective locking device for each of said legscomprising a nut nesting in the leg, and a screw passing from its headthrough the respective post, threaded through the nut, and bearingagainst the leg.

6. The scaffold of claim 1 in which each of said end support sectionshas its posts connected by a plurality of vertically spaced rungs spacedabove said side linkages, and in which removable platform means isprovided for placing at selected levels between said end supportsections on said rungs, the end portions of said platform means and therungs of said end support sections detachably interlocking with oneanother when said platform means is placed in working position betweensaid end support sections in a manner holding said end support sectionsagainst movement endwise of and relative to said platform means, theinterlock between said platform means and said rungs being released byvertical movement of said platform means relative to said rungs.

7. A collapsible scaffold comprising, removable platform means, twovertical end ladder sections each comprising two posts connected by aplurality of vertically spaced rungs, parallel side linkages operativelyconnected between said ladder sections near the lower end thereof andbelow the level of a majority of said rungs so that said ladder sectionsmay be brought close together to a collapsed storage position or beexpanded to a fully spaced working position wherein said platform meansmay be placed at selected levels between said ladder sections to besupported by the rungs thereof, the end portions of said platform meansand the rungs of said ladder sections detachably interlocking with oneanother when said platform means is placed in working position betweensaid ladder sections in a manner holding said ladder sections againstmovement endwise of and relative to said plat form means, the interlockbetween said platform means and said rungs being released by verticalmovement of said platform means relative to said rungs, said parallellinkages at each side of said scaffold comprising respective upper andlower parallel toggle mechanisms which jackknife upwardly at verticallyspaced elbows midway between said ladder sections and a respectivevertical con necting bar extending between said connecting bars wherebycollapsing of the scaffold may be effected by pulling said bracing barupwardly after removing said platform means, a pair of slide blockssleeved on said vertical connecting bars and bearing against theunderside of the elbow of the upper toggle mechanisms when the scaffoldis in expanded working position, and a pair of diagonal knee braces foreach side of the scaffold pivotally connected at their upper ends to therespective slide block and at their lower ends to the lower ends of theposts on the corresponding side of the scaffold.

References Cited by the Examiner UNITED STATES PATENTS Chenoweth 182152X Waltz 182152 Dirks 182--152 Thomas 182-452 Mitchell 182-222 X HARRISONR. MOSELEY, Primary Examiner.

1. A COLLAPSIBLE SCAFFOLD COMPRISING, AN EXPOSED PAIR OF VERTICAL ENDSUPPORT SECTIONS EACH INCLUDING A PAIR OF LATERALLY SPACED POSTS,PARALLEL SIDE LINKAGES CONNECTED BETWEEN THE POSTS OF SID END SECTIONFOR VERTICAL JACKKNIFING ACTION WHEREBY THE END SECTIONS MAY BE EXPANDEDTO A FULLY SPACED WORKING POSITION OR BROUGHT CLOSE TOGETHER TO ACOLLAPSE STORAGE POSITION, EACH OF SAID PARALLEL SIDE LINKAGES HAVINGUPPER AND LOWER PARALLEL TOGGLE MECHANISMS, EACH SID UPPER TOGGLEMECHANISM INCLUDING A CENTER UPPER ELBOW SECTION AND A PAIR OF UPPERTOGGLE ARMS PIVOTALLY CONNECTED TO THE UPPER ELBOW SECTION AND TO THEEND POSTS AT THE RESPECTIVE SIDE OF THE SCAFFOLD, AND EACH SAID LOWERTOGGLE MECHANISM INCLUDING A CENTER LOWER ELBOW SECTION AND A PAIR OFLOWER TOGGLE ARMS PIVOTALLY CONNECTED TO THE LOWER ELBOW SECTION AND TOTHE END POSTS AT THE RESPECTIVE SIDE OF THE SCAFFOLD, A RESPECTIVEVERTICAL CONNECTING BAR IN EACH OF SAID PARALLEL SIDE LINKAGES EXTENDINGBETWEEN THE UPPER AND LOWER ELBOW SECTIONS THEREOF, A RESPECTIVE SLIDEBLOCK SLEEVED ON EACH OF